What happens when the intake pressure drops below 20 psi during relay pumping?

When the intake pressure drops below 20 psi during relay pumping, the main concern is the risk of cavitation. Cavitation occurs when the pressure in the pump drops sufficiently, causing the liquid to vaporize, leading to the formation of bubbles. When these bubbles collapse within the pump, it can result in significant damage and reduced efficiency.

Maintaining an adequate intake pressure is crucial for proper pump operation. If the pressure falls below recommended levels, not only does the risk of cavitation increase, but the pump's performance may deteriorate, leading to potential operational failure. Therefore, understanding the critical limits for intake pressure helps in preventing damage to the pump and ensuring efficient water delivery during firefighting operations.